Callouse plane

ABSTRACT

A callous plane  1  having a blade head  2  and a handle  3  is disclosed, where callous plane  1  has an underside facing the body surface of a user when in working position, and an upper side facing away from said underside, and where a holding device  4  with a lower holding part  7  and an upper holding part  9  is provided in the blade head  2,  in which a blade  5  can be held in such a manner that its cutting edge  6  intended for use to shave off callous skin is located on the underside of callous plane  1.  To provide a callous plane  1  that is safer and easier to handle, and less complex to manufacture, it is proposed that lower holding part  7  be connected to handle  3  and display an upward-pointing seat  8  for blade  5,  and that upper holding part  9  hold blade  5  tightly in seat  8  with the help of a fixing device.

The invention relates to a callous plane having a blade head and ahandle, where the callous plane has an underside facing the body surfaceof the user when in working position, and an upper side facing away fromsaid underside, and where a holding device with a lower holding part andan upper holding part is provided in the blade head, in which a bladecan be held in such a manner that its cutting edge intended for use toshave off callous skin is located on the underside of the callous plane.

Callous planes display a razor-like, sharp blade, which should belocated in the callous plane with particular protection and as safely aspossible, meaning, among other things, in dimensionally and positionallystable fashion. These blades customarily display two cutting edges,located on opposite sides of the blade. For example, a customary callousplane of the kind mentioned in the opening paragraph displays a holdingdevice in which the blade is fastened to an upper holding part by alower holding part, as a result of which the blade is covered fromabove. On the underside, however, the lower part forms a discontinuityof shape, where the cutting edge and its corners project dangerously.

To protect the blade better, EP 1 216 664 A2 proposes that the blade beembedded in a holding device made of plastic. In this context, theholding device and the blade form an integral unit, which is fastened tothe callous plane. Although the corners of the cutting edge are coveredin this way, the spare cutting edge expediently remains free, apart fromits corners, constituting a corresponding risk of injury, since the unithas to be rotated through 180° on the callous plane in order to use thespare cutting edge. A further disadvantage is the complexity of theprocess for embedding the blade in an exact plastic moulding, thisadditionally entailing the problem of adhesion between the metallicmaterial of the blade and the plastic, as well as the necessary, secureholding of the extremely thin, hard and sharp-edged blade in the plasticbed, meaning that dangerous, premature loosening of the blade cannot beruled out. In addition, the fit of the unit on the callous plane canbecome loose as a result of rotation of the unit for use of the sparecutting edge.

The object of the invention is therefore to provide a callous plane ofthe kind mentioned in the opening paragraph that is less complex tomanufacture and safer to handle.

The object is solved by providing a callous plane of the kind mentionedin the opening paragraph, the lower holding part of which is permanentlyconnected to the handle and displays an upward-pointing seat for theblade, and whose upper holding part holds the blade tightly in the seatwith the help of a fixing device.

In this way, a relatively uncomplicated design solution is proposed thatdoes not provide for a two-part nature of the holding device on theunderside, thus meaning that no displacement or loosening of the holdingparts can occur on the underside. Furthermore, this makes it possible toavoid shoulders or other discontinuities of shape on the underside,which, according to the prior art, are formed by the lower holding partwhen the upper holding part is connected to the handle, and which candangerously catch when using the plane on elevated areas of skin, forexample, thus possibly leading to dangerous jumping of the callousplane. Furthermore, the blade is integrated in the lower profile lineand does not project dangerously beyond it. This fact can additionallybe exploited for conceiving an attractive design.

Consequently, it is advantageous if, in a development, the underside ofthe blade head can transition smoothly from the lower holding part intothe underside of the handle. The lower holding part can moreover bejoined to the handle in one piece. Thus, a continuous profile line isproposed, which further facilitates handling of the callous plane, thusmaking it safer. This makes it possible, for example, for the pitch,i.e. the angle at which the blade slides over the body surface to betreated, to be changed safely, without elevated callous skin catching orgetting stuck in discontinuities of shape on the underside of thecallous plane, such that the callous plane can unexpectedly jump as aresult of being torn away from these elevations. In addition, this makesit possible to create a particularly attractive, aesthetic shape with acontinuous profile line, this increasing the general acceptance of acallous plane.

In a preferred development, the lower holding part can cover the entireunderside of the held blade, apart from the middle section of thecutting edge intended for use. This avoids a danger of injury by thespare cutting edge from the underside, this particularly being likely tooccur when returning the callous plane to its starting position, in thatthe callous plane is usually moved in the cutting direction of the sparecutting edge during this process. Furthermore, this again contributes toan attractive design.

From its top side, the blade head can essentially cover the held blade,apart from a middle section of its cutting edge. This permits safer andeasier handling of the blade from above, e.g. when fixing the blade bypressing the upper holding part against the lower holding part.Moreover, in a further embodiment, the profile line of the upper sidecan transition smoothly from the blade part into the handle. This can,in turn, contribute to enhancing the design of the callous plane.

The underside of the upper holding part and the upper side of the lowerholding part can display curved shapes running roughly parallel to eachother, the neutral axis of which runs in the working direction of thecallous plane, such that the held blade is located between the holdingparts under bending stress. Bending of the blade increases thedimensional stability of the blade. Furthermore, the bent blade actslike a leaf spring between the holding parts, pressing the holding partsagainst the fixing means yet to be described, such that the holdingparts can be held in a more stable position relative to each other.

In this context, provision can be made, in accordance with customarycallous planes, for the holding parts to be laterally curved upwards,and for the working direction to run in the longitudinal axis of thecallous plane, from the blade head to the handle. Easy introduction offorce into the blade via the handle is possible in this context. Theworking direction can, however, also run parallel to the underside andperpendicular to the longitudinal axis, as a result of which the callousplane is moved sideways and thus capable of reaching areas of the bodysurface that are otherwise difficult to reach. Furthermore, provisioncan be made for the holding device to be rotatable into differentworking directions, preferably into the two working directions mentionedabove, and/or for the blade to be insertable into the seat in such a waythat its cutting edge points in a desired working direction.

In a development of the callous plane according to the invention, thelower holding part displays a blade opening, through which the cuttingedge of the blade can be passed in such a way that at least a middlelongitudinal section of the cutting edge projects beyond the edge of theblade opening on the underside of the lower holding part by a smalldistance perpendicular to the working direction. In this context, thecontour of the blade opening can, for example, correspond to a circulararc with a radius running in the working direction. This distanceultimately determines the maximum thickness of the particles of callousskin to be shaved off. This distance can be adjustable, e.g. in that theblade can be pushed farther out through the blade opening.

Furthermore, additional, laterally arranged covers can be provided forlaterally covering the side edges without a cutting edge and/or thespare cutting edge of the blade.

The seat can be designed as a trough in the upper side of the lowerholding part, where the blade opening for exposing the middle area ofthe cutting edge intended for use is located on the base of the troughon the underside of the lower holding part.

Preferably, the bend radius of the underside of the lower holding partcan be designed to be smaller than the bend radius of the underside ofthe upper holding part, at least in the area of the blade opening. As aresult, the held blade is bent correspondingly more strongly than theunderside of the lower holding part, thus projecting farther beyond theblade opening in the middle. Furthermore, the underside of the lowerpart can also be slightly bent in the longitudinal direction, such thatan underside with a slight convex arch results. Due to this archedunderside, the callous plane adapts more easily, and thus more safely,to the area of the body to be treated. Furthermore, the longitudinalsection of the cutting edge projecting through the opening is thus moreeasily accessible from below and therefore needs to project less farthrough the opening in order to shave off callous skin.

The fixing device preferably displays a guide device for guidedinsertion of the blades into the seat, and for inserting the two holdingparts into each other. This guide device can, for example, display guideprongs that are located at the corners of the seat and extend upwards,where the held blade and the upper holding part laterally rest againstthe guide prongs. As a result, the held blade is held on several sides,meaning that the blade can safely be pressed against the lower holdingpart, particularly while simultaneously building up bending tension inthe blade, since the blade cannot slip out of the seat laterally. In adevelopment, the sides of the guide prongs against which the held bladelies can be of pyramidal design, this facilitating insertion of theblade into the seat.

To enable safe insertion of the blade into the seat, a development ofthe invention provides an insertion trough on both longitudinal sides ofthe seat for inserting the blade, held between two fingers, into theseat. These insertion troughs are expediently covered by the upperholding part, as a result of which the user is guarded against anypossible projection of the blade.

In an advantageous development, the two holding parts are connectable bya plug-in connection on one side and have a snap-in connection on theopposite side. In this context, the plug-in connection can display twoparallel plug-in projections on the upper holding part, which are adistance away from each other, extend in the working direction and canbe guided against a stop under two corresponding retaining projectionsthat are a distance away from the base of the seat and from each other,where the side faces of the projections that face each other slide oneach other according to the principle of the inclined plane. Once theblade has been mounted in the seat, the plug-in projections of the upperholding part can be inserted under the retaining projections of thelower holding part and locked in place on the lower holding part in apivoting movement by pressing the two holding parts together. As aresult of this pivoting movement, the side faces of the projections thatface each other slide over each other, this being facilitated by slopingthese side faces. Other designs of the side faces are also conceivable,such as a convex side face of the retaining projection that slides on aside face of the plug-in projection of corresponding, concave design.Instead of via a plug-in connection, the upper holding part can be fixedto the lower holding part in pivoting fashion via a joint. Expediently,a section of the blade can be slid under the retaining projections forinsertion in the seat. The blade is fixed in the seat as a result andcan be pressed more safely against the lower holding part by the upperholding part.

In another embodiment of the fixing device, a tongue-and-groove guidecan be provided, by means of which, as described in more detail below,the upper holding part can be guided via the lower holding part,preferably in the working direction. In this context, thetongue-and-groove guide can display a guide rail and a guide groove witha dovetail-type cross-section, for example, as a result of which atighter fit of the guide rail in the guide groove is achievedperpendicular to the longitudinal direction, and the risk of the upperholding part expanding under the contact pressure of the blade isminimised. In another design, the cross-section of the guide can displaya unilateral dovetail shape with inside groove surfaces that run roughlyparallel to each other and at an angle other than 90° to the grooveopening, as a result of which only one undercut is thus formed. Thisundercut can be located on the lower inside groove surface in thiscontext. The tongue-and-groove guide can furthermore be provided onlateral inside surfaces of the lower holding part, as a result of whichthe upper holding part is correspondingly located on the inside, in orabove the seat for the blade, and/or on lateral outside surfaces of thelower holding part. As a result, the upper holding part can, for fittinginto the tongue-and-groove guide, reach over the lower holding part fromabove and thus completely cover the seat, and consequently the heldblade, from above.

In another embodiment of the fixing device, a combination of the fixingmethods described above is proposed, i.e. preferably of thetongue-and-groove guide and the plug-in connection. It goes withoutsaying that the scope of the invention also covers other fixing methodsthat hold the blade in the seat in suitable fashion by means of theupper holding part.

The fixing device can furthermore display snap-in means, by means ofwhich the upper holding part and the lower holding part can besnap-fitted to each other. It should preferably be possible for theupper holding part to be snap-fitted by the snap-in means withoutfurther tools, by pressing it against the lower holding part. To thisend, the one holding part can display at least one snap hook pursuant tothe prior art. In this context, the snap hook can be located laterallyon one of the holding parts and laterally reach around the other holdingpart for snap-fitting, its free end with the transverse hook end sectionlying under bending stress against the side of the other holding partfacing away from the one holding part. In this context, a recess can beprovided at this point, being engaged by the transverse hook end sectionat least in such a way that it does not project beyond the underside ofthe blade head. The end of the snap hook can furthermore display anotherextension, preferably running at right angles to the hook end andperpendicular to the working direction, by means of which it engages anopening or the like provided in the other holding part, as a result ofwhich a positive and non-positive connection can be achieved between thetwo holding parts. In another embodiment, the snap hook can displaylateral extensions which, after overcoming a projection or the likelocated on the other holding part by elastic bending of the snap hook,can engage lateral recesses, such as pockets or the like, provided onthe other holding part.

A pressure hollow for pressing the upper holding part against the lowerholding part can be provided on the upper side of the upper holdingpart, in order to ensure a firm hold for a pressure-exerting finger ofthe user. This pressure hollow can furthermore be used for pressing ofthe callous plane against an underlying surface by the finger of theuser, this permitting the easy and controllable application of pressureof the callous plane against the underlying surface. This pressurehollow is preferably of ergonomic design. Furthermore, the pressurehollow can be located on the free end of the blade head, and thusremotely from the cutting edge intended for use. Furthermore, thesnap-in means, particularly the snap hook, can be designed and locatedin such a way that they can be released by operating the pressurehollow.

In a development, a through-passage for collecting and ejectingshaved-off callous skin particles is provided in the upper holding part,said through-passage being located above the blade opening when inworking position. The through-passage expediently widens conicallytowards the upper side of the upper holding part, the inner wall of thethrough-passage facing towards the free end of the blade head displayinga run-off slope, via which the shaved-off callous skin particles can runoff in a direction opposite the working direction. This prevents callousskin particles from sliding in between the blade and the holding part,thereby blocking the blade.

The handle of the callous plane can display a handle part at its freeend and a connecting section at its end facing the blade head. In thiscontext, an eyehole leading from the upper side to the underside can belet into the connecting section in order to give a view of the bodysurface of a user to be treated. The eyehole can be laterally borderedby two webs arranged in the manner of a fork. The eyehole canfurthermore widen conically towards the top in order to permit thewidest possible view of the surface to be treated as a result. Amagnifier at least partly filling the eyehole can be provided in theeyehole for optical magnification of the view of the surface to betreated, this facilitating accurate and safe working.

The handle part can be ergonomically adapted to the hand of the user. Tothis end, one possible embodiment of the handle part essentially displaytwo sections, a section for the ball of the thumb, extending to the freeend, and a section for the finqers, adjacent to the connecting section.In this context, lateral, convex padded grips can be provided on thesection for the ball of the thumb for adaptation to the palm of the userand/or finger recesses can be provided in the section for the fingers.

The surface of the handle part can expediently be made, at least inpart, of anti-slip and/or supple material. Coating with an anti-slipmaterial is also conceivable. The handle part lies particularly securelyin the user's hand as a result.

The section for the fingers can preferably display several fingerrecesses around the circumference. In the event of a rectangularcross-section of the section for the fingers, for example, fingerrecesses can be provided on all four outer surfaces. As a result, whenrotated in the hand, the callous plane can be securely held in at leastfour positions, meaning that the callous plane can be safely guided overthe skin surface with the handle in various positions in the hand. Thisis particularly advantageous if the underside of a part of the body isto be treated with the callous plane, such that the underside of thecallous plane with the cutting edge of the blade points upwards againstthe direction of gravity.

The callous plane can be made of plastic. The callous plane canpreferably be manufactured as an injection moulding. In this context,the lower holding part can be connected to the handle in one piece.Furthermore, the upper holding part can be connected to the lowerholding part in one piece, e.g. via a film hinge.

The present invention is described in more detail below on the basis ofthree practical examples and an associated drawing. The Figures show thefollowing:

FIG. 1 A perspective top view of a first practical example of a callousplane, with an upper holding part,

FIG. 2 A perspective top view of the callous plane according to FIG. 1,without upper holding part and with inserted blade,

FIG. 3 A bottom view of the callous plane according to FIG. 1, withblade,

FIG. 4 A perspective top view of the upper holding part of the callousplane according to FIG. 1,

FIG. 5 A schematic representation of a cross-sectional area according tothe point marked by line A-A in FIG. 3,

FIG. 6 A perspective top view of a second practical example of thecallous plane according to the invention, without upper holding part andwith inserted blade,

FIG. 7 A perspective top view of the upper holding part of the callousplane according to FIG. 6,

FIG. 8 A schematic representation of a cross-sectional area of thecallous plane according to FIG. 6, without upper holding part and withinserted blade in the free end area,

FIG. 9 A schematic representation of a cross-sectional area as in FIG.8, but with inserted upper holding part,

FIG. 10 A schematic representation of a middle longitudinal sectionalarea of the free end of the blade head,

FIG. 11 A perspective top view of a third practical example of thecallous plane according to the invention, with an upper holding part,

FIG. 12 A perspective top view of the callous plane according to FIG.11, without upper holding part and with inserted blade,

FIG. 13 A perspective bottom view of the callous plane according to FIG.11, without upper holding part,

FIG. 14 A perspective top view of the upper holding part of the callousplane according to FIG. 11, and

FIG. 15 A perspective bottom view of the upper holding part of thecallous plane according to FIG. 11.

Based on FIGS. 1 to 5, a first practical example of a callous plane 1according to the invention is explained, indicating working direction X.FIG. 1 shows callous plane 1 with a blade head 2 and a handle 3 in aperspective top view, where callous plane 1 displays an underside,facing the skin surface of a user to be treated when in workingposition, and an upper side. Provided in blade head 2 is a holdingdevice 4, in which a blade 5 can be held in such a way that its cuttingedge 6 for shaving off callous skin not shown here, which is hardlyvisible in this illustration due to being concealed, is located on theunderside of callous plane 1. Holding device 4 displays a lower holdingpart 7 with an upward-facing seat 8 for blade 5, and an upper holdingpart 9 for pressing and fixing blade 5 in seat 8 by means of a fixingdevice. In this context, lower holding part 7 is connected to handle 3in one piece. While seat 8 is concealed by upper holding part 9 in FIG.1, it is revealed in FIG. 2. Blade 5 is essentially covered by upperholding part 9, except for a middle area of cutting edge 6.

FIG. 2 shows a perspective top view of callous plane 1, without theupper holding part and with blade 5 located in seat 8. A customary blade5 with two cutting edges 6, 10 is shown here, where, in the positionillustrated here, cutting edge 6 is used, whereas the other, as sparecutting edge 10, is concealed by upper holding part 9 and, as will beexplained in more detail on the basis of FIG. 3, by lower holding part7. It goes without saying that other blade forms can also be used, forwhich modifications of the holding parts, obvious to a person skilled inthe art who is familiar with this teaching, would possibly be necessary.

FIG. 3 shows a bottom view of callous plane 1. The underside of lowerholding part 7 transitions continuously into the underside of handle 3in this context. Furthermore, the underside of blade head 2 covers heldblade 5, apart from a middle section of its cutting edge 6, where lowerholding part 7 displays a blade opening 11, through which part ofcutting edge 6 of blade 5 passes. The underside of upper holding part 9and the upper side of lower holding part 7 run roughly parallel to eachother and display a curved shape, the neutral axis of which runs roughlyin working direction X of callous plane 1. As a result, blade 5, locatedbetween holding parts 7, 9, is subjected to bending stress, by means ofwhich blade 5, acting in the manner of a leaf spring, forces the twoholding parts 7, 9 apart against fixing means to be described in moredetail. This achieves greater positional stability of holding parts 7,9, and of blade 5 located therein.

Furthermore, the undersides of the two holding parts 7, 9 are curved,where, as indicated in the drawings, the bend radius of the underside oflower holding part 7 is smaller, at least in the area of blade opening11, than the bend radius of the underside of upper holding part 9. As aresult, blade 5 displays a more strongly curved elastic line than thearea around blade opening 11, meaning that the blade projects fartherbeyond blade opening 11 in the middle than towards the edge. Thispermits targeted and fine shaving of callous skin particles.

FIG. 4 shows a perspective top view of upper holding part 9. In thiscontext, upper holding part 9 displays two plug-in projections 12, whichextend in working direction X and can each be passed under two retainingprojections 13, shown in FIG. 2, and against a stop 14, where the sidefaces of projections 12, 13 that face each other slide over each otheraccording to the principle of the inclined plane. To this end, thecorresponding side face 15 of plug-in projections 12 in the practicalexample illustrated here is designed as a concave side face 15 with aninward-leading radius. Retaining projections 13 display a distance fromthe base of the seat that is adapted to plug-in projections 12. As canfurther be seen in FIG. 2, the corners of cutting edge 6 of insertedblade 5 pass under retaining projections 13. The corners are covered asa result. This furthermore holds blade 5 in a stable position.

Furthermore, a guide device is provided for guided insertion of blade 5into seat 8, and for inserting the two holding parts 7, 9 into eachother. In this context, the guide device displays guide prongs 16, whichare located at the corners of seat 8 and extend upwards. Held blade 5rests laterally against guide prongs 16, as a result of which blade 5 isheld in dimensionally and positionally stable manner in the blade plane.Furthermore, as shown in FIG. 1, laterally extending guide projections32 of upper holding part 9 likewise rest laterally against guide prongs16, meaning that improved positional stability of blade 5 is likewiseachieved in this way.

The end of upper holding part 9 opposite guide prongs 16 displays twoguide hooks 17, which, as can be seen in FIG. 1, reach over the free endof lower holding part 7 at the face end when in installed position, thisachieving further improvement of the positional stability of upperholding part 9, as well as of blade 5 mounted between holding parts 7,9. Furthermore, upper holding part 9 is provided with a snap hook 18,which is located between and at a parallel distance from the two guidehooks 17 in the manner of a leaf spring and likewise reaches over thefree end of lower holding part 7 at the face end. In this context, snaphook 18 engages a recess 19 in the underside of lower holding part 7 insuch a way that it rests against the underside under bending stress.Provision is additionally made for side faces 31, with which guideprongs 16 laterally rest against blade 5 and upper holding part 9 whenin holding position, to taper pyramidally upwards in order to facilitatethe insertion of blade 5 and the engaging of upper holding part 9 inlower holding part 7.

A pressure hollow 20 is additionally provided on the upper side of upperholding part 9 for pressing callous plane 1 against an underlyingsurface (not shown). Since this pressure hollow 20 is located directlyabove blade 5 when in installed position, the user can insert a fingerhere to specifically exert pressure on blade head 2. Furthermore, thetwo holding parts 7, 9 can be pressed together safely via this pressurehollow 20 by the user acting on the upper and lower side of blade head2.

As can be seen in FIG. 3, lower holding part 7 displays two insertionrecesses 21 on its longitudinal sides, these facilitating insertion ofblade 5 into seat 8. Insertion recesses 21 are covered by upper holdingpart 9 when the two holding parts 7, 9 are assembled, such that the sideedges of the inserted blade without a cutting edge are likewisecompletely covered from above.

Callous plane 1 is provided with a through-passage 22 for collecting andejecting shaved-off callous skin particles (not shown), wherethrough-passage 22 is located above blade opening 11 when in workingposition. On its inner wall facing away from the handle, thisthrough-passage 22 displays a run-off slope 23, which is clearly visiblein FIG. 4 and runs in the direction opposite to working direction X.This facilitates the ejection of shaved-off callous skin particles,which run off via run-off slope 23, simultaneously preventing theseparticles from dangerously congesting blade 5.

As schematically indicated in FIG. 2, handle 3 of callous plane 1essentially displays three sections, a connecting section 24, a sectionfor the fingers 25 and a section for the ball of the thumb 26. In thiscontext, connecting section 24 is provided with a triangular eyehole 28,laterally bordered by two forklike webs 27, for viewing the surface tobe treated, which lies downstream of cutting edge 6 in working directionX. Eyehole 28 is expediently designed with a slight conical tapertowards the bottom.

The section for the fingers 25 and the section for the ball of the thumb26 form the actual handle area of handle 3 and are ergonomically adaptedto the user's hand. To this end, in this embodiment of callous plane 1,the section for the fingers 25 displays finger recesses 29, and thesection for the ball of the thumb 26 displays laterally located, convexpadded grips 30. These padded grips 30 are preferably made of anti-slipand/or supple material. Anti-slip coating of padded grip 30 is alsoconceivable. Handle 3 can likewise be partly or completely provided withan anti-slip surface or made of anti-slip material.

The section for the fingers 25 displays an essentially rectangularcross-section with four side walls with rounded edges, where each of theside walls is provided with a finger recess 29, such that the overallcross-sectional shape is as illustrated schematically in FIG. 5. As aresult, a secure and ergonomically adapted fit of handle 3 in the handof the user is still possible when handle 3 is in a rotated position inthe hand of the user, such that callous plane 1 can be gripped securelyand guided safely in various positions in the hand.

FIGS. 6 to 10 illustrate a second practical example of callous plane 1.In contrast to the previously described example, callous plane 1 in thiscase displays a different fixing method for fixing upper holding part 9on lower holding part 7. To this end, as can be seen in the perspectivetop view of upper holding part 9 in FIG. 7, lateral guide rails 33 areprovided in upper holding part 9, extending in the longitudinaldirection.

It can be seen in FIG. 6, a perspective top view of lower holding part 7with inserted blade 5, that guide prongs 16 display guide grooves 34,adapted to guide rails 33, for guiding upper holding part 9 duringconnection of the two holding parts 7, 9, where upper holding part 9 canbe slid over lower holding part 7 in working direction X. Guide grooves34 run accordingly on the inner side of guide prongs 16 and in thelongitudinal direction of lower holding part 7. In order to bendinserted blade 5 as intended when joining the two holding parts 7, 9, itis expedient that, in order to bend blade 5, upper holding part 9 can,in a first step, be guided from above, i.e. perpendicular to the bladeplane, against blade 5 and, in a further step, connected to lowerholding part 7 by engaging guide rails 33 and guide grooves 34 inworking direction X. To this end, gaps a are provided between guiderails 33, which face towards the free end of callous plane 1 ininstalled position, and guide projections 32, through which end guideprongs 16 can be passed perpendicular to the blade plane.

FIGS. 8 and 9 each schematically illustrate a cross-sectional areathrough blade head 2, roughly at the level of end guide prongs 16,without and with upper holding part 9 inserted in seat 8, respectively.This is intended to demonstrate the position of blade 5 in seat 8between holding parts 7, 9. In FIG. 8, blade 5 lies loosely in seat 8,distance b being provided between guide grooves 34 and the upper side ofinserted blade 5 to prevent lateral slipping of blade 5 into guidegrooves 34. In FIG. 9, guide rails 33 of upper holding part 9 areinserted in guide grooves 34 of lower holding part 7, thedownward-curved shape of upper holding part 9 pressing blade 5downwards, such that blade 5 rests against the underside of upperholding part 9 under tension, at least in a middle area.

The representations shown in FIGS. 8 and 9 are merely intended toillustrate the principle according to which blade 5 is held in holdingdevice 4. Consequently, other embodiments realising this principle alsofall within the scope of this invention.

In the second practical example, guide rails 33 and guide grooves 34display a dovetail-type cross-section. As a result, the forcetransmitted through downward-curved blade 5 to upper holding part 9 isintroduced obliquely into lower holding part 7 in force direction K,roughly in accordance with the curved upper side of upper holding part9. In contrast to horizontal introduction of a force generated by thetension of blade 5, this at least essentially reduces the danger ofpossible expansion of lower holding part 7.

FIG. 10 shows a schematic representation of a longitudinal sectionalarea in the centre line of the free end of blade head 2, with snap hook18 projecting beyond the end of lower holding part 7. In contrast to thefirst practical example, snap hook 18 in this case reaches aroundsnap-in projection 35, provided on the end of lower holding part 7, andinto a snap-in groove 36, resting against snap-in projection 35 and/orsnap-in groove 36, preferably under tension. In the event of motion ofupper holding part 9 relative to lower holding part 7 in a directionopposite to working direction X, this prevents snap hook 18 fromreleasing itself prematurely from snap-in projection 35, meaning thatthe two holding parts 7, 9 are reliably fixed in blade head 2. Thisfixing is additionally intensified by the frictional forces occurringbetween guide rail 33 and guide groove 34, and by the tensioned blade 5.

To protect against premature release of snap hook 18 from snap-inprojection 35, a thicker area 37 is provided in working direction X,preferably transitioning continuously into the remaining underside oflower holding part 7 in working direction X.

The thicker area can, as not shown here however, extend farther on theunderside in the direction opposite to the working direction, over thesnap hook, such that the snap hook thus engages an opening or groove.For easier release of the snap hook, the snap hook can furthermore reacharound the snap-in projection with clearance in such a way that, byapplying pressure to the upper holding part perpendicular to the workingdirection, the snap hook can be released from the snap-in groove andguided out over the snap-in projection in a direction opposite to theworking direction. It goes without saying that the first practicalexample, and also the third one following now, can display a similarsnap hook design with snap-in groove and/or thicker area.

Based on FIGS. 11 to 15, a third practical example of callous plane 1according to the invention will now be described, where FIGS. 11, 12 and15 show a perspective top view and FIGS. 13 and 14 a perspective bottomview of the callous plane or of individual components of the callousplane. In this context, the third practical example essentially differsfrom the previous practical examples in that it has a different designof the fixing device, which is in principle designed as a combination ofthe previously described fixing methods, i.e., in addition to a numberof design modifications, primarily a tongue-and-groove guide and aplug-in connection. In this context, a tongue-and-groove guide isprovided in the free end section of blade head 2, while the end of bladehead 2 facing handle 3 displays a plug-in connection.

As can be seen in FIG. 12, where lower holding part 7 is illustrated,and in FIGS. 14 and 15, showing upper holding part 9, upper holding part9 displays two plug-in projections 12, extending in working direction X,which can each be guided under two retaining protections 13 of lowerholding part 7 and against a stop 14. In this context, the side faces ofprojections 12, 13 that face each other are arranged to slide over eachother according to the principle of the inclined plane. Retainingprojections 13 expediently display a distance from the base of seat 8that is adapted to plug-in projections 12, so that the corners ofcutting edge 6 of blade 5 inserted in seat 8 can be passed underretaining projections 13. This covers the dangerous corners of cuttingedge 6, additionally holding blade 5 in a stable position.

In contrast to the second practical example, lateral guide rails 33 are,as illustrated in FIGS. 12 and 13, located on the free end of lowerholding part 7 and extend in their longitudinal direction only up toinsertion recess 21 provided for inserting blade 5 into seat 8.Accordingly, guide grooves 34, not visible in FIGS. 14 and 15 due tobeing covered, are provided for upper holding part 9, theircross-section and length being adapted to guide rails 33. Thecross-section of guide rails 33 and of guide grooves 34 displays acustomary, dovetail-type shape, with the help of which displacementperpendicular to the longitudinal direction is prevented. To simplifythe object, the dovetail shape is designed with only one undercut inthis context, the transverse extension of guide rails 33 extendingobliquely downwards.

To connect the two holding parts 7, 9, upper holding part 9 can beplaced from above on seat 8, over lower holding part 7, only in such away that it projects so far beyond the free end of lower holding part 7that guide rails 33 of lower holding part 7 are positioned in front ofthe start of guide grooves 34, and guide grooves 34 of upper holdingpart 9 can be slid over guide rails 33 of the lower holding part. Inthis context, a blade 5 inserted in seat 8 is pressed down towards thebase of the seat, building up bending stress in the process.Introduction of guide rails 34 into corresponding guide grooves 33 inworking direction X of callous plane 1 enables guided displacement ofupper holding part 9 in working direction X, such that plug-inprojections 12 of upper holding part 9 can be passed under retainingprojections 13 of lower holding part 7 until plug-in projections 12 restagainst stop 14.

For tighter positioning, guide hooks 17 are, in contrast to the firstpractical example, each fitted with an additional guide hook projection38, which extends in working direction X and, in assembled state ofholding parts 7, 9, engages a correspondingly adapted guide hook recess39 located on the underside of lower holding part 7. In this context,guide hook projection 38 and guide hook recess 39 are preferablydimensioned in such a way that guide hook projection 38 does not projectdownwards beyond the underside of lower holding part 7.

The snap hook 18 provided is, as in the preceding practical examples,located between and at a parallel distance from guide hooks 17, in themanner of a leaf spring, and reaches over the free end of lower holdingpart 7 at the face end. As a result, snap hook 18 can be moved back andforth to a certain degree about a pivoting axis perpendicular to workingdirection X. In contrast to the preceding examples, snap hook 18displays laterally arranged snap-in wings 40, which, for the purpose oflocking, can each be guided via snap-in projection 35, located on theunderside of lower holding part 7, into snap-in groove 36, which islocated downstream thereof in working direction X and designed as apocket. To release it, snap hook 18 can be pressed downwardsperpendicular to working direction X, so that snap-in wings 40 can beguided over the respective snap-in projections 35 by displacing upperholding part 9 in the direction opposite to working direction X. As canparticularly be seen in FIGS. 11 and 13, the fixing device, with guidehooks 17 and snap hooks 18 leading to the underside of lower holdingpart 7, is dimensioned in such a way that callous plane 1 displays asmooth, continuous underside that therefore does not interfere with theuse of callous plane 1.

The practical examples of callous plane 1 illustrated here aremanufactured as a two-part, plastic injection moulding with twocomponents, the lower holding part 7, connected to handle 3, and theupper holding part 9. It is also conceivable to manufacture the callousplane as a one-part injection moulding, in that the lower and the upperholding part are connected to each other in one piece via an integrallymoulded joint, such as a film hinge.

LIST OF REFERENCE NUMBERS

-   1 Callous plane-   2 Blade head-   3 Handle-   4 Holding device-   5 Blade-   6 Cutting edge-   7 Lower holding part-   8 Seat-   9 Upper holding part-   10 Spare cutting edge-   11 Blade opening-   12 Plug-in projection-   13 Retaining projection-   14 Stop-   15 Side face-   16 Guide prong-   17 Guide hook-   18 Snap hook-   19 Recess-   20 Pressure hollow-   21 Insertion recess-   22 Through-passage-   23 Run-off slope-   24 Connecting section-   25 Section for the fingers-   26 Section for the ball of the thumb-   27 Web-   28 Eyehole-   29 Finger recess-   30 Padded grip-   31 Side face-   32 Guide projection-   33 Guide rail-   34 Guide groove-   35 Snap-in projection-   36 Snap-in groove-   37 Thicker area-   38 Guide hook projection-   39 Guide hook recess-   40 Snap-in wing-   a Distance-   b Distance-   x Working direction-   K Force direction

1. Callous plane having a blade head and a handle, where the callousplane has an underside facing the body surface of a user when in workingposition, and an upper side facing away from said underside, and where aholding device with a lower holding part and an upper holding part isprovided in the blade head, in which a blade can be held in such amanner that its cutting edge intended for use to shave off callous skinis located on the underside of the callous plane wherein the lowerholding part is permanently connected to the handle and displays anupward-pointing seat for the blade, and in that the upper holding partholds the blade tightly in the seat with the help of a fixing devicecharacterised in that the fixing device displays snap-in means forsnap-fitting the upper holding part to the lower holding part. 2.Callous plane according to claim 1, characterised in that the undersideof the blade head transitions smoothly from the lower holding part intothe underside of the handle.
 3. Callous plane according to claim 1,characterised in that the lower holding part covers the entire undersideof the held blade, apart from a middle section of the cutting edgeintended for use.
 4. Callous plane according to claim 1, characterisedin that the blade head essentially covers the upper side of the heldblade, apart from a middle section of the cutting edge intended for use.5. Callous plane according to claim 1, characterised in that theunderside of the upper holding part and the upper side of the lowerholding part display curved shapes running roughly parallel to eachother, the neutral axis of which runs in a working direction of thecallous plane, such that the held blade is located between the holdingparts under bending stress.
 6. Callous plane according to claim 1,characterised in that the lowerholding part displays a blade opening,through which the cutting edge of the blade can be passed in such a waythat at least a middle longitudinal section of the cutting edge projectsbeyond the edge of the blade opening on the underside of the lowerholding part by a small distance perpendicular to the working direction.7. Callous plane according to claim 6, characterised in that theundersides of both holding parts are curved, where the bend radius ofthe underside of the lower holding part is smaller than the bend radiusof the underside of the upper holding part, at least in the area of theblade opening.
 8. Callous plane according of claim 1, characterised inthat the fixing device displays a guide device for inserting the bladeinto the seat, and for inserting the two holding parts into each other.9. Callous plane according to claim 8, characterised in that the guidedevice displays guide prongs that are located at the corners of the seatand extend upwards, where the held blade and the upper holding partlaterally rest against the guide prongs.
 10. Callous plane according toclaim 1, characterised in that the fixing device displays atongue-and-groove guide, by means of which the upper holding part can beguided over the lower holding part.
 11. Callous plane according to claim10, characterised in that the tongue-and-groove guide displays a guiderail and a guide groove with a dovetail-type cross-section.
 12. Callousplane according to claim 1, characterised in that a pressure hollow isprovided on the free end of the blade head and on the upper side of theupper holding part.
 13. Callous plane according to claim 1,characterised in that a through-passage for collecting and ejectingshaved-off callous skin particles is provided in the upper holding part,where the through-passage is located above the blade opening when inworking postition.
 14. Callous plane according to claim 1, characterisedin that the handle displays a handle part at its free end and aconnecting section at its end facing the blade head, where an eyeholeleading from the upper side to the underside is let into the connectingsection in order to give a view of the body surface of a user to betreated.
 15. Callous plane according to claim 1, characterised in that,for ergonomic adaptation, the handle part displays a section for theball of the thumb with convex padded grips in its free end area and/or asection for the fingers with a finger recess on its end facing towardsthe connecting section.
 16. Callous plane according to claim 15,characterised in that the section for the fingers displays a rectangularcross-section shape with finger recesses provided on all sides. 17.Callous plane according to claim 16, characterised in that the callousplane is made of plastic.
 18. canceled